Load lock system for charged particle beam imaging

ABSTRACT

A load lock system for charged particle beam imaging with a particle shielding plate, a bottom seal plate and a plurality of sensor units is provided. The sensor units are located above the wafer, the shield plate is designed to have a few number of screws, and the bottom seal plate contains no cable, no contact sensors and fewer screws used. In the invention, the system is designed to improve the contamination particles from components in the load lock system of charged particle beam inspection tool and also to simplify its assembly.

FIELD OF THE INVENTION

The present invention relates to a patterning device holding apparatus.More particularly, it relates to a patterning device holding apparatusfor a charged particle beam system.

BACKGROUND OF THE INVENTION

The following description and examples are not admitted to be prior artby their mention in this Background section.

In order to enhance the yield and reliability of the semiconductordevices such as integrated circuits (ICs) and memory devices, examiningthe defects on the patterned wafer for the avoidance of them has beensignificant. The physical defects, such as foreign particles, scratchdefects, residual defects, bridging defects and so on, cause the devicesto fail electrically, for example, the short or open circuit.Furthermore, since deep sub-micrometer node devices are developed, newand more complicated manufacturing structures such as a dual damascenestructure and a fin-shaped field effect transistor (FinFET) structureare utilized in the semiconductor devices. Therefore, new types ofdefects including latent defects, for instance, chemical mechanicalpolishing (CMP) scores, under-layer leakage, under-etch, missing, voids,voltage contrast (VC) defects, and non-virtual defects (NVDs) occurduring the manufacturing phase. Besides, while the less than 20 nmmanufacturing process is on line, it has been a big challenge for theobservation of nano-size semiconductor devices. It is consequence thatthe optical inspection apparatus has been stretched to the limit of itscapability at the inspection of these defects and tiny devices. Herein,the issue is effectively addressed by a charged particle beam apparatus,for example, an electron beam tool based on a scanning electronmicroscope (SEM), and the semiconductor manufacturing and the yieldenhancement can be optimized by the apparatus.

In the fabrication of a semiconductor device using a charged particlebeam inspection system, however, the contamination particles areinevitably formed and thus settle on wafers being processed therein. Forexamples, the inspected device in EBI usually remains residual particlesarising from the components in a load lock system of e-beam inspectiontool when the device is inspected for an electron beam imaging (EBI) forearly defect identification. Referring to FIG. 1, a transitional bottomseal plate 100 for holding a sample, comprises a cable 101 lying in agroove 103 on the plate 100 for the signal transduction from a pluralityof contact detecting units 102, which are used to detect the position ofthe sample, and a plurality of screws 104 to keep the plate 101 and thecable 101 from moving. These components can be the sources of thecontamination particles.

Such contamination problem significantly lowers the product yield andthe reliability of a semiconductor device and becomes more severe withincreasing higher integration levels and with increasing a processingefficiency. Therefore, it is desirable to provide a method and systemcapable of improving such the problem for the examination of chargedparticle beam system.

The present invention provides a load lock system with a patterningdevice holding apparatus for the charged particle beam imaging e-beaminspection tool to improve the aforementioned shortcomings of theconventional patterning device holding apparatus and reduce thepossibility of damaging the semiconductor devices.

SUMMARY OF THE INVENTION

This summary is provided to comply with 37 C.F.R. § 1.73, requiring asummary of the invention briefly indicating the nature and substance ofthe invention. It is submitted with the understanding that it will notbe used to interpret or limit the scope or meaning of the claims.

The present invention is relates to a seal load lock apparatus forholding a sample for the charged particle beam imaging.

In one embodiment, the apparatus comprises a particle shield platedisposed above the sample for shielding from at least one undesiredparticle from at least one component coupled with the apparatus; and abottom seal plate located below the device for holding the sample. Theapparatus further comprises at least one position detecting unit with anemitter for projecting a light beam on the sample and a receiver forreceiving the reflected signal form the sample to identify the positionof the sample, wherein the position detecting unit separated from thebottom seal plate, wherein the position includes at least a verticalposition of the sample. In addition, the apparatus can be coupled to aload lock system that is used to transfer the device between a vacuumchamber and an atmosphere environment, wherein the load lock system isfor use in an inspection tool. The apparatus further can be installed ina SORIL SEM.

The apparatus can also comprise a top seal plate disposed above thesample to form a room to seal the sample. In addition, the particleshield plate is inside the room and above the sample. The apparatusfurther comprises a view port located between the position detectingunits and the sample to pass the light beam and a reflected signal fromthe sample. The position detecting unit in the apparatus can be a lasersensor. In another embodiment, the position detecting unit can be acontact sensor when the positioned on the bottom seal plate.

Another embodiment relates to a bottom seal load lock apparatus forsupporting a device, comprising a particle shield plate located abovethe device for shielding from at least one undesired particle at leastone undesired particle from at least one component coupled with theapparatus, wherein the plate has up to a maximum of three screws to fix;a bottom seal plate disposed below the device to support the device,wherein the plate has up to a maximum of three screws to fix; and aplurality of position detecting units separated from the bottom sealplate for detecting a geometric position of the device by projecting alight beam on the device.

Another embodiment relates to an inspection apparatus involving a loadlock system, comprising a charged particle beam emitter for emitting aprimary charged particle beam; a condenser lens for condensing theprimary charged particle beam; an objective lens for focusing theprimary charged particle beam to probe a sample; a plurality ofdeflection electrodes for scanning said charged particle beam probeacross a surface of the sample; a detector for detecting secondarycharged particles generated from the sample surface; and a bottom sealload lock apparatus, which is coupled to a load lock system that is usedto transfer the device between a vacuum chamber and an atmosphereenvironment, for supporting a device, comprising: a particle shieldplate located above the device for shielding from at least one undesiredparticle at least one undesired particle from at least one componentcoupled with the apparatus, wherein the plate has up to a maximum ofthree screws to fix; a bottom seal plate disposed below the device tosupport the device, wherein the plate has up to a maximum of threescrews to fix; and a plurality of position detecting units separatedfrom the bottom seal plate for detecting a geometric position of thedevice by projecting a light beam on the device.

Another embodiment relates to method for improving contaminationparticles from components in a charged particle beam inspection tool,comprising: utilizing a holding apparatus having a seal room for sealinga sample without any position detecting unit in the room; utilizing ashielding plate disposed in the room with a maximum of three screws tofix the plate to shield at least one undesired signal; and utilizing abottom seal plate disposed in the room for supporting the sample with amaximum of three screws for fixing the plate. In addition, the methodcomprises the seal room formed by a top seal plate and the bottom sealplate.

The embodiments of the systems mentioned above will be furtherconfigured as described herein. Furthermore, the embodiment of themethod described above may be performed by any of the systems describedherein.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be readily understood to those skilled in theart by the following detailed description in conjunction with theaccompanying drawings, wherein the same or like reference numeralsdesignate the same or like structural elements, and in which:

FIG. 1 is a schematic diagram illustrating a top-view of a bottom sealplate of holding apparatus in prior arts;

FIG. 2 is a schematic diagram illustrating a cross-section of a sealload lock apparatus for holding a sample in accordance with oneembodiment of the present invention;

FIG. 3 is a schematic diagram illustrating a cross-section of pluralnon-contact position defecting units coupled with the seal load lockapparatus;

FIG. 4 is a schematic diagram illustrating a top-view of a bottom sealplate located in the seal load apparatus in accordance with oneembodiment of the present invention;

FIG. 5 is a schematic diagram illustrating a particle shielding platelocated in the seal load apparatus in accordance with one embodiment ofthe present invention;

FIG. 6 is a schematic diagram illustrating a cross-section of a sealload lock apparatus with a top seal plate in accordance with oneembodiment of the present invention;

FIG. 7 shows a schematic diagram illustrating a top-view of a top sealplate located in the seal load apparatus in accordance with oneembodiment of the present invention;

FIG. 8 is a schematic diagram illustrating a cross-section of a loadlock system in accordance with one embodiment of the present invention;and

FIG. 9 shows a schematic diagram illustrating a scanning electronmicroscope in accordance with one embodiment of the present invention.

While the invention is susceptible to various modifications andalternative forms, specific embodiments thereof are shown by way ofexample in the drawings and may herein be described in detail. Thedrawings may not be to scale. It should be understood, however, that thedrawings and detailed description thereto are not intended to limit theinvention to the particular form disclosed, but on the contrary, theintention is to cover all modifications, equivalents and alternativesfalling within the spirit and scope of the present invention as definedby the appended claims.

DETAILED DESCRIPTION OF THE INVENTION

The preferred embodiment herein disclosed is not intended to beexhaustive or to limit the invention to the precise form disclosed.Rather, it is chosen and described in order to best explain theinvention so that others skilled in the art may utilize its teachings.Besides, in alternative embodiments, those components identical to thecomponents of the first embodiments are given the identical referencenumerals without giving another reference numerals for simplicity.

Referring now to FIG. 2, one embodiment of a seal load lock apparatus200 for holding a wafer 201 is described below. The seal load lockapparatus 200 including a bottom plate 202 disposed on a seat 205 withplural wafer standoffs 203 to hold a wafer 201. A particle shieldingplate 204 is located above the wafer 201 in the apparatus 200 to shieldthe undesired particles from the above components (not shown) coupledwith the apparatus 200. Furthermore, a set of non-contact positiondetecting units 301, which is separated from the bottom plate 202, withan emitter 302 for projecting a light beam 304 to detect the wafer 201and a receiver 303 for receiving the signals 305 from the wafer 201 areused to identify the position of the wafer 201, especially the verticalposition, as shown in FIG. 3. Therein, the particle shielding plate 204has a plurality of holes corresponding to the non-contact positiondetecting units 301 to allow the light beam 304 and the signals 305passing through. The reflected signal 305 at least contains theinformation of the Z-axis position (i.e., the vertical position) of thewafer 201, which can be distinguished by a processing unit (not shown)via the receiver 303 to identify the position of wafer 201. Preferably,the non-contact position detecting units 301 is a laser sensor. It iscontemplated that above-mentioned embodiments of the load lock apparatusdescribed herein, along with derivations thereof, may be utilized inother processing systems and with other work piece supports.

Alternatively, rather than the non-contact position defecting units 301,a set of contact position defecting units may be disposed on the bottomplate, as shown in FIG. 1. The contact position defecting units 102disposed on the bottom plate 100 to physically connect with the wafer201 to identify the position of the wafer 201. Therein, a cable 101 isconnected with the contact position defecting units 102 to transfer thesignal form the units 102 to the processing unit (not shown).

In the embodiment depicted in FIG. 2, in order to reduce thecontamination particles from the components in the load lock apparatus200, the bottom plate 202 and the particle shielding plate 204 can alsobe fixed by at the maximum of three screws 401 and 501 to the apparatus200, respectively, as shown in FIGS. 4 and 5. Referring to FIG. 5, a setof holes 502 located on the edge of the particle shielding plate 204corresponding to the non-contact position detecting units 301 isprovided to pass through the light beam 304 and the signals 305.

FIG. 6 depicts another embodiment of a load lock apparatus arrangement.The arrangement is substantially similar to the apparatus of FIG. 2described above, except a top seal plate 206 is located in the top sideof the particle shielding plate 204, which forms a seal room 208(enclosed by the dash line) with the bottom seal plate 202. Furthermore,the particle shielding plate 204 and the wafer 201 are enclosed in theroom 208, the non-contact position detecting units 301 is outside theroom 208 for removing one of the possible sources of the contaminationparticles in the room 208. Referring to FIG. 7, a view port 701 isprovided in the top seal plate 206 for passing the light beam 505 andthe reflected signals 506 to the receiver 504. As the above-mentioned,the particle shielding plate 204 also needs to have corresponding holesto pass the signals.

In another embodiment, the above-mentioned embodiments of the load lockapparatus can be coupled to a load lock system 800 as shown in FIG. 8,which is used to transfer the wafer 201 between the load lock apparatus200 (marked by a bracket) and the low vacuum environment for theinspection of the wafer 201. The turbo pump 801 is used to vacuum theload lock apparatus 200 until at least 10⁻⁵ torr and then, the wafer 201is transferred from the low vacuum environment into the load lockapparatus 200. The damper 802 is used to alleviate the effect on thewafer 201 in the vibration from the pump 801. A turbo pump gate valve803 is provided to switch on/off the turbo pump 801. The light signals304 from the non-contact position defecting units 301 and the reflectedsignals 305 from the wafer 201 are passing through the channel 804(enclosed by the dash line), including the view port 701 and holes 502,to identify the position of the wafer 201. Furthermore, the load locksystem 800 with the load lock apparatus can be installed into aninspection tool, which is adopted from Chen et al. U.S. patentapplication Ser. No. 12/257,304 filed in Oct. 23, 2008 entitled “ACharged Particle Beam Apparatus”. It is a modified Swing ObjectiveRetarding Immersion Lens (SORIL).

FIG. 9 depicts a cross sectional view of one embodiment of an inspectionsystem 900. The system 900 includes a charged particle beam generator901 for generating a primary electron beam 910, a condenser lens module902 for condensing the primary electron beam 910, a probe formingobjective lens module 903 for focusing the primary electron beam 910into an electron beam probe, an electron beam deflection module 907 forscanning the electron beam probe across the surface of sample 911, acharged particle detector module 908 for detecting secondary electronsalong with backscattered electrons from the sample 911 upon beingbombarded by the electron beam probe and forming an image of the sample911 accordingly, and a bottom seal load lock apparatus 912 for holdingthe sample 911 thereon during the imaging process. In the embodiment,the disclosed bottom seal load lock apparatus 912 is integrated in theinspection system 900 and is configured for supporting the wafer 911thereon for imaging. Accordingly, the exemplary bottom seal load lockapparatus 912 of the present invention may apply to the scanningelectron microscope to program.

One embodiment of a method for improving contamination particles fromcomponents in a charged particle beam inspection tool, which ispracticed with the apparatus of FIG. 2. It comprises the following idea:reducing the component parts and/or removing the components, whichpossibly are the source of contamination particles. Accordingly, amaximum of three screws are used to fix a particle shielding plate 204and a bottom seal plate 202, respectively, to the disclosed seal room208 for holding the wafer 201. Furthermore, the position detecting units301 for detecting the position of the wafer 201 are removing from theroom 208, and now detect the wafer 201 from outside the room 208. It iscontemplated that the method may be practiced on processing systemshaving different configurations and for other types of applications forreducing the contamination particles from components in the inspectiontool as mentioned above.

In summary, the present invention provides an apparatus and methodtargeted for improving the residual contamination particles on thesample. Advantageously, both of the application of the simplifiedcomponents consisting in the bottom load lock apparatus and removing theposition detecting units from the apparatus allows the apparatus toeasily reduce the degree of contamination particles.

Although the present invention has been described in accordance with theembodiments shown, one of ordinary skill in the art will readilyrecognize that there could be variations to the embodiments and thosevariations would be within the spirit and scope of the presentinvention. Accordingly, many modifications may be made by one ofordinary skill in the art without departing from the spirit and scope ofthe appended claims.

1-26. (canceled)
 27. An apparatus comprising: a holder configured to hold a sample; a particle shielding plate disposed above the holder; and a position detecting unit including an emitter configured to project a light beam toward the holder, wherein the particle shielding plate includes an opening corresponding to the position detecting unit.
 28. The apparatus of claim 1, further comprising a bottom plate disposed below the holder.
 29. The apparatus of claim 28 further comprising a top seal plate disposed above the holder configured to form a room to seal the sample.
 30. The apparatus of claim 29, wherein the particle shielding plate is inside the room and above the sample.
 31. The apparatus of claim 27, wherein the position detecting unit is one of a plurality of position detecting units that are separated from the bottom seal plate and are configured to identify a position of the sample, the position including at least a vertical position of the sample.
 32. The apparatus of claim 31, further comprising a view port located between the plurality of position detecting units and the sample to pass the light beam and a reflected signal from the sample.
 33. The apparatus of claim 31, wherein the position detecting unit includes a laser sensor.
 34. The apparatus of claim 28, further comprising at least one position detecting unit being a contact sensor positioned on the bottom plate.
 35. The apparatus of claim 29, wherein the position detecting unit is configured to identify a position of the sample, the position detecting unit being positioned either external or internal the room, wherein the position includes at least a vertical position of the sample.
 36. The apparatus of claim 35, wherein the position detecting unit includes a contact sensor positioned on the bottom plate.
 37. The apparatus of claim 35, wherein the emitter is configured to project the light beam on the sample and the position detecting unit further includes a receiver for receiving the reflected signal from the sample to identify the position of the sample, the position detecting unit being separated from the bottom plate.
 38. The apparatus of claim 37 further comprising a view port located between the position detecting unit and the sample to pass the light beam and a reflected signal from the sample.
 39. The apparatus of claim 37, wherein the position detecting unit includes a laser sensor.
 40. The apparatus of claim 27, wherein the apparatus is configured to be coupled to a load lock system to enable transfer of the sample between the apparatus and a low vacuum environment, wherein the load lock system is configured for use in an inspection tool.
 41. The apparatus of claim 27, wherein the load lock apparatus is configured to be installed in a SORIL SEM.
 42. A method for shielding components in a charged particle beam inspection tool from contamination particles, comprising: irradiating, by a position detecting unit, a sample provided on a holder through an opening in a particle shielding plate that is disposed above the holder.
 43. The method of claim 42, wherein the position detecting unit includes an emitter configured to project a light beam toward the sample, wherein the particle shielding plate includes an opening corresponding to the emitter.
 43. The method of claim 42, further comprising: providing the sample in a room, the room formed at least partially by a bottom plate disposed below the holder and a top seal plate disposed above the holder.
 44. The method of claim 42, further comprising: receiving a reflected signal from the sample.
 45. The method of claim 42, further comprising: identifying a position of the sample, the position including at least a vertical position of the sample.
 46. The method of claim 42, further comprising: passing a light beam and a reflected signal from the sample through a view port located between the position detecting unit and the sample. 